Tortusk

The Tortusk is a creature in the Keen 4 mod The Terror from Outer Space by Dr. Colossus. This is one of the several native lifeforms of the planet Phaelox. The Totusk prefers dark habitats, so it is often found in caves. Their diet consists mostly of deadly acid fungi which thrive in these caves. Alone, these creatures can cause no harm to Keen but they do have the uncanny ability to push Keen into hazards.

The official help text states:

Although this creature looks pretty dangerous it is in reality a harmless vegetarian. They are so tame that you can even ride on them.